TWO NEW SPECIES OF MEGASTIGMUS DALMAN ( HYMENOPTERA : TORYMIDAE ) FROM INDIA , WITH A REVISED KEY TO INDIAN SPECIES

The genus Megastigmus was described by Dalman in 1820 with Pteromalus bipunctatus Swederus as its type species. This genus belongs to the subfamily Megastigminae of the family Torymidae. This genus consists of 133 species worldwide of which 20 species were reported from the Oriental Region and 8 species from India (Noyes, 2003; Sure shan, 2009). Most species are phytophagous but some are parasitic in gall-forming insects (Narendran, 1994; Noyes, 2003). In this paper, two new species viz., Megastigmus sonneratiae Narendran and Girish Kumar sp. nov. emerged from the leaf galls of the mangrove plant Sonneratia apetala Buch. Ham and Megastigmus dharwadicus Narendran and Vastrad sp. nov. emerged from the galls of Eucalyptus, are described. The new species M. dharwadicus is an important parasitoid of Leptocybe invasa Fisher and LaSalle which is a serious invasive pest (Narendran, 2007; Mendel et al., 2004) of Eucalyptus in India and adjacent countries. A revised key to separate Indian species of M egastigmus is also provided.


INTRODUCTION
The genus Megastigmus was described by Dalman in 1820 with Pteromalus bipunctatus Swederus as its type species.This genus belongs to the subfamily Megastigminae of the family Torymidae.This genus consists of 133 species worldwide of which 20 species were reported from the Oriental Region and 8 species from India (Noyes, 2003;Sure shan, 2009).Most species are phytophagous but some are parasitic in gall-forming insects (Narendran, 1994;Noyes, 2003).In this paper, two new species viz., Megastigmus sonneratiae Narendran and Girish Kumar sp.nov.emerged from the leaf galls of the mangrove plant Sonneratia apetala Buch.Ham and Megastigmus dharwadicus Narendran and Vastrad sp.nov.emerged from the galls of Eucalyptus, are described.The new species M. dharwadicus is an important parasitoid of Leptocybe invasa Fisher and LaSalle which is a serious invasive pest (Narendran, 2007;Mendel et al., 2004) of Eucalyptus in India and adjacent countries.A revised key to separate Indian species of M egastigmus is also provided.
The type specimens are deposited at the 'National Zoological Collections' of the Zoological Survey of India, Kolkata (NZSI).

MATERIALS AND METHODS
The leaf galls of the plant Sonneratia apetala and Eucalyptus were collected and reared in the laboratory from which the parasites emerged out.The specimens were card mounted and studied under a stereozoom microscope (Wild Heerbrugg made in Switzerland) and drawings were made using the drawing tube of the microscope.

Megastigmus sonneratiae
Head: Width in dorsal view (Fig. 3) 2.44x length, 1.76x as long as pronotal width; head width in anterior view (Fig. 2) 1.26x its median length; vertex convex, cross striate, with bristles black; POL 2.5x OOL; occiput moderately emarginate; vertex with six large brown setae on occipital margin submedially; an oblique line of strong setae on each parascrobal space (Fig. 2); clypeus demarcated with lower margin incised.Antenna inserted a little above level of ventral margin of eye; antennal formula 11173; scape not reaching front ocellus, pedicel as long as F 1; ring segment shorter than half of pedicel; Fl shorter than F2; length of clava longer than preceding two segments.
Thorax : Pronotum 1.66x as broad as long, very finely transversely striated; mesoscutum with anterior one third smooth and shiny, remaining part striate reticulate, striae stronger than those of pronotum; scapulae transversely striated; mesoscutum with 5 pairs of setae, each scapulae with 7 setae on outer margin (arranged in two rows; 3 pairs outer; 4 pairs towards middle), 2 setae near inner margin.Scutellum as long as broad, transversely reticulate, with a median shallow sulcus extending upto middle; scutellum with 3 pairs of setae (one pair at the frenal area); frenal furrow indistinct, frenum longitudinally rugose.Dorsellum smooth.Propodeum (Fig. 4) 0.55x length of scutellum, with submedian grooves and few median shallow short grooves; surface of propodeum transversely and irregularly reticulate.Forewing (Fig. 1) length 2.54x its maximum width; costal cell narrow with pubescence in distal half, proximal half bare; basal cell with some pubescence (about 8 setae in number), open basally; speculum very narrow, almost absent, closed below; MV a little shorter than half length of costal cell, subequal to PMV; 2.3x as long as STY; STY 1.64x as long as broad.Legs with minute pubescence with the following parts having thick setae: fore femur, fore tibia, mid tibia, hind coxa and hind tibia.
Gaster : As long as thorax; first tergite deeply emarginate on posterior margin; ovipositor sheath as long as combined length of thorax and gaster, 2x as long as thorax, 2x as long as gaster.
Host: Emerged from the leaf galls of Sonneratia apetala Buch.Ham (Family: Lithraceae), a mangrove plant commonly known as 'Mangrove Apple' , which is one of the most common plants in Sunderbans mangrove forests.
Lower clypeal margin incised in the middle (in M. viggianii lower clypeal margin not distinctly bilobed or incised in the middle); (3).Fl shorter than F2 (in M.
Gaster: Sessile, smooth, 1.8x as long as hind tibia, 0.97x as long as thorax, O.SSx as long as ovipositor sheath laterally.Ovipositor sheath 1.78x as long as gaster, 3.23x as long as hind tibia.
Host: Emerged from the tender stem and leaf galls of Eucalyptus (Family: Myrtaceae).

Etymology:
The species is named after the district from were the type specimens collected.Discussion : This new species comes close to Megastigmus kashmiricus Sureshan, 2009 but distinctly differs from it in having: (1).Propodeum (Fig. 9) with a cross carina (in M. kashmiricus no such cross carina on propodeum); (2).Scape not reaching front ocellus (in M. kashmiricus scape exceeds level of vertex); (3).Propodeal spiracle separated by its own diameter from hind margin of metanotum (in M. kashmiricus spiracle separated by 1.Sx its own diameter from hind margin of metanotum); (4).Malar space 0.32x as long as eye (in M. kashmiricus malar space half as long as eye); (S).

Rec. zooz. Surv. India
This new species also comes close to Megastigmus albizziae Mukerji, 19S0 but distinctly differs from it in having: (1).POL 2.Sx OOL (in M. albizziae POL as long as OOL); (2).SMV 1.92x as long as MV (in M. albizziae SMV about 7x as long as MV); (3).STY 0.44x as long as MV (in M. albizziae STY about as long as MV); (4).Antennal club 2.6x as long as preceding segment (in M. albizziae club about 1.7x as long as preceding segment); (S).Scape 2.17x as long as pedicel (in M. albizziae scape 3.7Sx as long as pedicel).
This new species also differ from the Australian species Megastigmus eucalypti Girault, 1915 in having: (1).Propodeum completely pale yellowish brown (in M. eucalypti propodeum dark with transverse yellow spot on each side of meson anteriorly); (2).Notauli not black (in M. eucalypti notauli black); (3).Dorsum of gaster mostly black with pale yellow on sides of T1 and T2 (in M. eucalypti dorsum of gaster with several suffused blackish stripes across proximal half); (4).Pronotum yellowish brown with small brownish black patches (in M. eucalypti pronotum lemon yellow); (S).Head width in anterior view 1.19x its height (in M. eucalypti head width l.4x its height in anterior view); (6).Clava 3x or a little more than 3x as long as wide (in M. eucalypti clava distinctly shorter than 2.4x as long as wide).
Key to the Indian species of Megastigmus Dalman (Modified from Narendran et al., 2003;Sureshan, 2009) 1. Male: General body colour luteous; head with a large transverse black patch on vertex extending nearly to eyes, front and face whitish; antennae black with scape luteous; mesosoma with a black stripe which is attenuate in the middle and extends from the anterior border of the pronotum nearly to

SUMMARY
Two new species of Megastigmus Dalman viz., M. sonneratiae Narendran and Girish Kumar sp.nov.and M. dharwadicus Narendran and Vastrad sp.nov.are described from India and their affinities to the closest relatives are discussed.A revised key to the Indian species of Megastigmus is also provided.